1. Field of the Invention
The present invention relates generally to hand-held digital wireless data communication and computing devices of the types generally referred to as hand-held computers, personal digital assistants, cellular telephones, pagers and the like and, more specifically, to the protocols used by such wireless devices for communicating and interacting with remote servers.
2. Description of the Related Art
A distinct category of electronic communication and computing devices increasingly referred to in the art simply as “wireless devices” is coalescing from the previously distinct fields of mobile computing and cellular telephony. The category includes devices commonly referred to as palmtop or hand-held computers, personal digital assistants, organizers, “smart” cellular telephones, pagers, and the like. Cellular and similar mobile telephones and telephone-like devices include computer application program-like functions, such as games, contact managers and e-mail. Personal digital assistants (PDAs) and other computer-like devices can include remote communication functions such as wireless networking for communicating e-mail and data. The convergence of wireless digital communication and mobile computing has given rise to wireless devices with substantial application program-like functionality.
There are presently few standards for wireless devices in the area of application layer protocols used by such wireless (client) devices for communicating with remotely located (server) computers, even though Internet Protocol (IP) may be the standard network layer protocol. For example, a server computer that implements an e-mail service may require that clients, such as the wireless devices described above, communicate with it using the Post Office Protocol (POP), but another server that implements an e-mail service may require that clients communicate with it using Internet Message Access Protocol (IMAP). An application program developer wishing to provide products to both users of POP-based email services and users of IMAP-based e-mail services must develop a separate version of the application for each protocol. Developing and maintaining multiple versions of the same application program to suit different users is inefficient and uneconomical for software developers.
Furthermore, different types of services almost invariably involve different protocols. For example, while a server that implements an e-mail service may require that clients communicate with it using POP, a server that implements a directory service (e.g., a database in which a user can search persons' names and addresses) may require that clients communicate with it using the Lightweight Directory Access Protocol (LDAP). As the number of types of application programs commercially available for wireless devices increases, so does the number of protocols a device must handle if it is to run more than one application program. Each time a user installs a new type of application program on his wireless device, the device is required to handle a new application layer protocol. The increase in the total amount of code installed in a device as a result of it handling additional application layer protocols is inefficient and wasteful of memory and other device resources. Because power consumption is a major concern in wireless devices, they typically have limited memory capacity and limited processing power.
One way of implementing some applications is through the use of Wireless Application Protocol (WAP). WAP is a communications protocol and a platform-neutral application environment. It can be built on any operating system, including PALM-OS, EPOC, WINDOWS CE, FLEXOS, OS/9, JAVA-OS, etc. Nevertheless, WAP requires the installation of a WAP Browser on the device, thus occupying a substantial amount of memory. Furthermore, the WAP Browser only works in conjunction with a remote server that executes the application.
It would be desirable to provide a more standardized mechanism for handling application layer protocols in wireless devices that simplifies the tasks of application program developers and is efficient in its use of memory and other device resources. The present invention addresses these problems and deficiencies and others in the manner described below.